“Sore Loser Laws and Congressional Polarization”

To enhance explanations for party polarization in the U.S. Congress, we focus on an unappreciated legal structure known as the sore loser law. By restricting candidates who lose partisan primaries from subsequently appearing on the general election ballot as independents or nominees of other parties, these laws give greater control over ballot access to the party bases, thus producing more extreme major party nominees. Using several different measures of candidate and legislator ideology, we find that sore loser laws account for as much as a tenth of the ideological distance between the major parties.